Stewart Butterfield talking to Jason Dean (back in October). On the topic of whether emoji and other visual items are just novelty:

In John Locke’s letters 350 years ago, he didn’t use any animated GIFs because he couldn’t. I’m not saying that he would have written letters in animated GIFs, but if he could have dropped a photo in to illustrate a point, he totally would have.

On the topic of email:

I can see email lasting tens of thousands of years, as preposterous as that sounds. If email is ever killed, it will be replaced with something that has all its virtues and all its problems as well. It’s an open system that anyone can participate in and that has a global name space. It’s a protocol that’s decades old and has thousands of clients that support it. It’s how you get the receipt after your Uber ride and a billion other things. But I think email is a lunatic thing to use inside an organization. None of its basic virtues—that anyone can use it, that it’s widely supported—matter inside a company. It’s a heterogeneous mix of the receipt from Uber and the request for time off and an invitation to a surprise party from an old friend and my mom giving me an update and someone looking for a job. Going through all that is really taxing. If I’m not well rested, it’s difficult for me to open my email.